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''Balaena'' is a genus of cetacean (whale) in the family Balaenidae. ''Balaena'' is considered a monotypic species, as it has only a single extant species, the bowhead whale (''B . mysticetus''). It was first described in 1758 by Linnaeus, who at the time considered all of the right whales (and the bowhead) as a single species. Historically, both the Balaenidae family and ''Balaena'' genus were known by the common name, "right whales", however ''Balaena'' are now known as bowhead whales.〔 "The taxonomy is not in doubt.... Concerning common names, the species was once commonly known in the North Atlantic and adjacent Arctic as the Greenland Right Whale. However, the common name Bowhead Whale is now generally used for the species."〕 Throughout history, the Balaenidae family has been the subject of great taxonometric debate. Authorities have repeatedly recategorized the three populations of right whale plus the bowhead whale, as one, two, three or four species, either in a single genus or in two separate genera. In the early whaling days, they were all thought to be a single species, ''Balaena mysticetus''. Eventually, it was recognized that bowheads and right whales were in fact different. Later, morphological factors such as differences in the skull shape of northern and southern right whales indicated at least two species of right whale—one in the Northern Hemisphere, the other in the Southern Ocean. As recently as 1998, Dale Rice, in his comprehensive and otherwise authoritative classification, ''Marine mammals of the world: systematics and distribution'', listed just two species: ''Balaena glacialis'' (the right whales) and ''Balaena mysticetus'' (the bowheads). A DNA study by Rosenbaum in 2000, and another study by Churchill in 2007 finally provided clear evidence to conclude that the ''three'' living right whale species do comprise a phylogenetic lineage, ''distinct from the bowhead'', and that the bowhead and the right whales are rightly classified into two separate genera. The right whales, therefore, are now officially in the ''Eubalaena'' genus. The fossil record of ''Balaena'', dating to the late Miocene, encompasses ten species known from finds in Europe, North America, and South America.〔(The Paleobiology Database ''Balaena'' entry ) accessed on 21 December 2010〕 ''Balena'', described by Scopoli in 1777, and ''Leiobalaena'', described by Eschricht in 1849, are junior synonyms of ''Balaena''. ==Taxonomy== * ''Balaena'' Bowhead whales * * † ''Balaena affinis'' (Pliocene; Red Crag Formation, UK) * * † ''Balaena montalionis'' (Piacenzian; Casina, Italy). * * ''Balaena mysticetus'', Bowhead Whale (Late Pleistocene to Modern) * * † ''Balaena ricei'' (Piacenzian; Rice's Pit, Yorktown Formation, Virginia, USA). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Balaena」の詳細全文を読む スポンサード リンク
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